code: def testRegression(self):
      input = readVector(join(filedir(), "spectrum", "input.txt"))
      expected = readVector(join(filedir(), "spectrum", "output.txt"))
  
      result = PowerSpectrum(size=len(input))(input)
      expected = [x * x for x in expected]
  
      # result = Spectrum(size=len(input))(input)
      # result = [x*x for x in result]
  
      self.assertAlmostEqualVector(result, expected, 1e-3)
  
file_path: essentia/test/src/unittests/standard/test_powerspectrum.py
imports: from essentia_test import *
label_desc: Use image node_id 1 for calling the TestPowerSpectrum obj's underlying member method code with example usage: obj.testRegression() without return types